Helmet Viscoelastic Foam Liner Reducing Angular Acceleration
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Solution Overview
Problem
Current sports helmets, particularly football helmets, have not effectively reduced the number of concussions despite improvements, as they primarily focus on linear acceleration and ignore angular acceleration, which is a significant contributor to head injuries during impacts.
Innovation Solution
The design incorporates a viscoelastic polymeric foam liner that reduces both linear and angular accelerations of the head by allowing the outer shell to move relative to the head cap, with a configuration of radially-oriented foam columns that absorb and distribute impact forces, enabling the shell to return to its initial position after an impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If helmet improvements focus on reducing linear acceleration through better cushioning in the liner area, then linear deceleration is reduced, but angular acceleration is not addressed and concussions continue unabated
Solution Approach 1:
The helmet liner is segmented into multiple independent foam elements (blocks, cylinders, or other shapes) arranged in a matrix pattern. Each element can deform independently to absorb linear impact forces while allowing rotational movement, thereby addressing both linear deceleration and angular acceleration simultaneously
Solution Approach 2:
The liner elements are designed to be dynamically responsive, changing their stiffness and deformation characteristics based on the type and magnitude of impact. This allows the liner to optimize its performance for both linear and rotational impacts, reducing both linear deceleration and angular acceleration as needed
2Force
If the liner is made more compliant to reduce linear acceleration, then linear impact forces are reduced, but the helmet may not provide sufficient rotational control
Solution Approach 1:
By dividing the liner into multiple discrete elements rather than using a single continuous layer, the system achieves rotational control through the collective behavior of segmented components. Each element maintains simplicity while the overall structure provides sophisticated rotational management
Solution Approach 2:
The same segmented liner structure serves multiple functions simultaneously: it absorbs linear impact forces through compression of individual elements while also managing rotational forces through the relative movement and deformation patterns of the element matrix, eliminating the need for separate rotational control mechanisms
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design significantly reduces the angular acceleration of the head, potentially lowering the incidence of concussions by addressing both contributors to head injury, thereby enhancing the protective capabilities of helmets.
Implementation Method 1
The liner exhibits energy absorbing radial compliance to reduce linear acceleration
Implementation Method 2
The liner exhibits energy absorbing radial compliance to reduce linear acceleration
Implementation Method 3
A returnable, energy absorbing liner located in-between the head cap and the outer shell exhibits circumferential compliance to reduce angular acceleration
Implementation Method 4
an outer shell which moves independently from the head cap and user's head
Data Source
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AI summary
A protective helmet includes a head cap, which surrounds and moves with a wearer's head, and an outer shell which surrounds the head cap. The outer shell is movable both radially and circumferentially relative to the head cap. An energy absorbing flexible liner is located between the head cap and the outer shell. The liner is attached to the outer shell and the head cap so that neither the head cap nor the head of the wearer is otherwise attached to the outer shell. The liner establishes a preset initial relative position and spacing between the head cap and the outer shell and compliantly absorbs energy imparted to the outer shell during a helmet impact to enable the outer shell to move relative to the head cap during the helmet impact and to be returned to the initial relative position with the head cap following the impact.